This is a little heart box that has sufficient space for you to install LEDs, batteries and few electronic components. You can feel free to modify it~

Components:
1) Red LED (dia. 3mm) , 2 pcs
2) 50 Ohm resistor (1/4 W), 1 pcs
3) 3D print components, 2 pcs
4) CR2032 battery holder, 1 pcs
5) CR2032 battery, 1 pcs
6) HDX contactless sensor, 1 pcs
7) Hot glue
8) Masking tape (Optional)

Required time: 30 mins - 1 hour